Method and apparatus for winding thread



Sept. 1, 1970 s E 3,526,368

METHOD AND APPARATUS FOR WINDING THREAD Filed June 10, 1968 INVENTOR.F/6,-3- GRADY HHSANDERS I %RNE? United States Patent 3,526,368 METHODAND APPARATUS FOR WINDING THREAD Grady H. Sanders, Spartanburg, S.C.,assignor to Deering Milliken Research Corporation, Spartanburg, S.C., acorporation of South Carolina Filed June 10, 1968, Ser. No. 735,922 Int.Cl. B65h 54/06 U.S. Cl. 242-18 8 Claims ABSTRACT OF THE DISCLOSUREMethod and apparatus for winding a continuous thread onto a rotatingsupport surface in a desired pattern wherein the tensional forcestending to displace the thread from the path in which it is laid on thesupport surface are minimized by imparting feeding force to the threadduring abrupt changes in the direction of the thread lay path and byreducing the force resisting linear movement of the thread onto thesurface.

This invention relates to method and apparatus for winding a continuousthread onto a rotating support surface in a desired pattern, and moreparticularly to an improved method and apparatus for forming annularreinforcing belts for use in the construction of pneumatic tires.

It is known to provide an annular reinforcing belt, or breaker strip,between the tread and carcass portions of a pneumatic tire to increaseits resistance to road hazards and to provide greater road stability andlonger Wear life for the tire. Such belts are generally composed of oneor more layers, or plies, of parallel, relatively inextensible, threadsor cords coated with or embedded in an insulating material, such asrubber, with the adjacent plies running in opposite directions anddiagonally to the centerline of the belt to provide increased strengthand longitudinal extensibility to the belt during use.

A particularly desirable method of producing such a belt, in that itminimizes the number of free ends of reinforcing thread in the belt andprovides a splice free belt construction, involves winding one or morecontinuous lengths of thread onto a rotating support surface havingafiinity for the thread, while employing thread guide means to traversethe rotating surface and adhesively secure the thread in a generallyzigzag path thereon. During the Winding operation, the belt is formed byincrementally displacing the zigzag thread path along the periphery ofthe support surface to build up a plurality of plies of parallel threadsextending generally diagonally to the direction of movement of thesupport surface.

Typical apparatus for continuously coating a moving thread and formingreinforcing belts therefrom is disclosed in U.S. Pat. No. 3,113,738 andincludes an extruder for applying an adhesive protective covering suchas unvulcanized rubber, to a longitudinally moving thread, and a supportdrum and traverse mechanism for winding the coated thread into areinforcing belt. The drum is rotated continuously to draw the coatedthread, by way of appropriate thread guide means, from the extruder andonto its peripheral surface, while the traverse mechanism isreciprocated across the surface to lay and adhesively secure the threadin the desired pattern.

In the use of a rotating drum and traverse mechanism of the typedescribed to produce continuous thread reinforcing belts, problems existin obtaining a uniform thread pattern on the drum surface during thewinding operation.

The tension imposed on the thread as it is longitudinally drawn onto thedrum and subjected to the action of the reciprocating traverse mechanismtends to dislocate the thread from the desired path or pattern in whichit is 3,526,368 Patented Sept. 1, 1970 laid on the drum. Dislocation ofthe thread from the lay path due to tensional forces acting on thethread is most pronounced at points of abrupt change in the direction ofthe lay path, and is particularly acute at the side edges of the drumwhere the corners of the zigzag thread path are laid and the linearvelocity of the thread momentarily approaches zero. As the traversemechanism moves away from the corners and the thread velocity rapidlyincreases, increased tension causes the thread corners to be pulledinwardly way from the edges of the drum, resulting in irregular threadpatterns in the belt. These irregular or non-uniform thread patternsproduce non-uniform loadcarrying characteristics in the tires in whichthe belts are incorporated which consequently cause excess vibration inthe tires and reduce their overall performance during use.

Although it would be possible to substantially reduce the tension on thethread being wound on the drum by providing means for positively feedingthe thread onto the drum from a point closely adjacent its surface, suchis not practical because of various factors which require that the speedof movement of the thread onto the drum surface be varied continuouslyto insure a uniform thread pattern during the formation of the belt.Such factors include variation in the cross-sectional size of the threadalong its length, gradual increase in the diameter of the annularsurface on which the thread is laid due to thread build-up on thewinding drum, variation in the length of the thread path leading to thedrum caused by the periodic displacement of the reciprocating traversemechanism from a centerline of the drum during winding, and theaforementioned abrupt changes in the direction of the thread lay path onthe surface of the drum. Additionally, if the rotational speed of thewinding drum is programmed to vary in response to temporary overfeed orunderfeed conditions of the extruder which coats the thread, thelongitudinal speed of the thread passing onto the drum must becorrespondingly varied.

It is therefore an object of the present invention to provide a methodand apparatus for Winding a continuous thread onto a rotating supportsurface in a desired pattern which overcomes the problems of the priorart.

It is another object of the invention to provide an apparatus forwinding a continuous thread onto a rotating support surface wherein thethread can be laid on the surface in a desired pattern with minimumaberration of the thread lay path due to tensional forces acting on thethread during the winding operation.

It is a more specific object to provide a rotating drum type windingapparatus for forming annular reinforcing belts from a continuous threadwherein tensional forces acting on the thread being wound on the drumare minimized to provide a more uniform thread pattern in the belt.

It is an additional object to provide a method of winding a continuousthread onto a rotating support surface in a desired pattern whereintensional forces tending to displace the thread from the pattern duringthe winding operation are minimized.

Certain objects of the invention have been stated, other objects willbecome apparent from the following discussion of the invention anddescription of the drawings, in which FIG. 1 is a schematic elevationview of a thread coating and winding apparatus employed in theproduction of reinforcing belts for pneumatic tires in which the novelfeatures of the present invention are incorporated;

FIG. 2 is an enlarged schematic perspective view of the belt formingdevice and adjacent thread guide components of the apparatus seen inFIG. 1, and showing in more detail the means for controlling operationof the forming device and thread guide components during the beltforming operation; and

FIG. 3 is an enlarged perspective view, with portions shown in section,of the thread guide roller for directing thread to the transversemechanism and winding drum shown on FIG. 2.

Referring more specifically to FIG. 1, the thread coating and windingapparatus for producing annular pneumatic tire reinforcing belts by acontinuous thread winding process generally includes a source of thread,such as a thread spool 12, an extruder 14 for coating the thread, a beltforming device 16, and guide means 18 for directing thread from theextruder 14 to the belt forming device 16. In operation, an uncoatedcontinuous cord or thread 22, which may be suitably composed of variousrelatively inextensible materials, such as fiber glass, rayon, cotton,polyester, wire and the like, is longitudinally directed by threadguides 24 from the supply spool 12 to the extruder 14 where the movingthread is coated, in conventional manner, with a protective coating,such as unvulcanized rubber. The rubber-coated thread 25, whichpossesses a tacky, pressure sensitive adhesive surface characteristic,is directed by thread guide means 18 to the belt forming device 16 whereit is wound into an annular reinforcing belt.

Details of the belt forming device 16 and the associated thread guidemeans 18 are best shown schematically in FIG. 2. Belt forming device 16includes a rotatable winding drum 26 having a cylindrical outer surface27 for supporting receiving thread, and a thread traverse mechanism 28positioned adjacent the drum surface. Drive means, generally indicatedat 30, are employed to rotate the winding drum 26 and simultaneouslyreciprocate the traverse mechanism 28 across the surface of the drum tolay the coated thread 25 on the surface in a generally zigzag path. Thespecific structural details of the thread traverse mechanism 28 and itsoperation are described and shown in copending United States applicationSer. No. 730,301, filed May 20, 1968, which is commonly assigned withthe present application.

Drive means 30 includes a variable speed motor 32, driven by a suitablepower supply, not shown, which is operatively connected by a belt andpulley arrangement 34 and gear train 36 to respective drive shafts 38,40 of the winding drum 26 and a barrel cam 42 of the traverse mechanism28. Operation of motor 32 simultaneously rotates the winding drum 26 andreciprocates a thread laying element 44 of the traverse mechanism acrossthe surface 27 of the drum to lay and adhesively secure the coatedthread in a zigzag thread path on the drum surface. During rotation ofthe drum, the path is incrementally displaced, due to the configurationof gear train 36, to produce an overlapping thread pattern P.

As seen in FIGS. 1 and 2, thread guide means 18 serves to longitudinallydirect thread from the extruder 14 to the traverse mechanism 28 andgenerally includes a pair of thread support guides 46, 47, threadcontrol means 50 and a thread guide roller 52 located adjacent thetraverse mechanism for supportably receiving and guiding the movingthread 25 thereto. Guide roller 52 (FIGS. 2 and 3) is preferablyconstructed of relatively dense material, such as stainless steel,plastic or the like, and is of willcient radius that its moment ofinertia tends to maintain rotary motion in the roller during periodswhen the linear speed of the thread on the drum surface approaches zero,as will be explained. Guide roller 52 is mounted for rotation on asupport shaft 54 by suitable bearing means, shown as a pair of ballbearings 55, 56 (FIG. 3), which are of a conventional type havingincreasing torque characteristics with increasing rotational speeds.

As seen in FIG. 2, the support shaft 54 is operatively connected bychange gears 57 and interconnected pulley and belt arrangements 58, 59to the barrel cam drive shaft 40. By this arrangement, variable speedmotor 32 simultaneously drives the winding drum, traverse mechanism, androtatable shaft 54 of the guide roller so that the speed of all threemay be varied simultaneously and proportionately by control means 50, aswill be explained,

thereby minimizing variations in tension on the thread passing from theroller 52 to the traverse mechanism and winding drum.

Control means 50 serves to vary the rate of movement of the winding drum26, traverse mechanism 28, and support shaft in response to variationsin the length of the thread path from extruder 14 to the traversemechanism 28 and comprises a pivotally mounted arm 62 which engages themoving thread 25 between the thread guide 47 and guide roller 52. Arm 62is of suflicient weight to maintain the thread in a V-shaped pathbetween the guide 47 and roller 52 and, as tension increases ordecreases in the thread path due to variations in the rate of extrusionfrom the extruder 14, the arm is pivotally displaced to lengthen orshorten the thread path between the extruder and winding drum. Spacedabove and below arm 62 and engageable thereby are solenoid switches 64,65 which are electrically connected by conductors 66 to the variablespeed control unit 67 of motor 32. Engagement of the switches by the arm62 serves to increase or decrease the motor speed, thereby maintainingthe arm between the switches and the length of the thread pathsubstantially constant.

In operation, the winding drum is rotated by motor 32 to draw coatedthread 20 from the extruder onto the surface of the drum. During beltformation, the traverse mechanism is reciprocated across the drumsurface to lay the longitudinally moving thread in a generally zigzagpath and build up a plurality of plies of parallel threads. As thereciprocating thread laying element 44 of the traverse mechanism reachesthe side edges of the drum to form the corners of the zigzag threadpath, the linear velocity of the thread passing onto the drum surfacequickly decreases, momentarily approaching zero. Due to the forceimparted to the rotating guide roller by the rotating shaft 54 and themoment of inertia of the guide roller, a feeding force is applied to thethread which develops a slack in the portion of the thread be tween theroller and the thread laying element. This slack is highly desirable forproper formation of the corners of the pattern in that it prevents asudden tension buildup and displacing jerk on the thread at the cornersas the traverse mechanism moves away from the side edges of the drum andthe linear velocity of the thread rapidly increases. By continuouslyrotating the support shaft of the guide roller, rotational force can beimparted to the roller during the critical period in which it has thetendency to slow down due to reduction in the linear velocity of thethread passing onto the drum surface, thereby insuring continuedmovement of the roller and thread and avoiding a sudden jerk on thethread as the traverse mechanism moves away from the corners. Rotationof the support shaft additionally reduces the overall frictional drag ofthe bearing members which resist rotation of the guide roller, therebyat all times reducing the tensional force required to draw the threadonto the drum while permitting variations in the linear speed of thethread to insure proper thread pattern formation.

By means of the present invention, and with a knowledge of the inertialcharacteristics of the roller and the weight of the thread being laid onthe drum, the rotational speed of the roller support shaft can bereadily adjusted to tune the guide roller for optimum thread patternuniformity in various tire belt constructions. By further simultaneouslyvarying the speed of movement of the winding drum, traverse mechanismand guide roller support shaft in proportionate amounts, the variationsin thread tension between the guide roller and winding drum can beminimized.

Although the apparatus of the present invention has been described andillustrated in the drawings as being employed to form annularreinforcing belts for pneumatic tires, it should be understood that theinvention may be adapted to other winding operations where it is desiredto lay a continuous thread on a support surface in a uniform patternwith minimum aberration of the pattern due to tensional forces acting onthe thread during winding.

The foregoing drawings and specification have set forth a preferredembodiment of the invention and, although specific terms have beenemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation.

That which is claimed is:

1. Apparatus for winding a continuous thread on a rotating supportsurface in a desired pattern including means defining a rotatablesupport surface for receiving thread, means for rotating said surfacedefining means to longitudinally draw thread onto the surface, a threadguide traverse mechanism positioned adjacent the surface and movablethereover to lay thread in a desired pattern, and thread guide means forlongitudinally directing thread to said traverse mechanism, said threadguide means including a guide roller positioned adjacent said traversemechanism for supportably receiving and guiding thread thereto, asupport shaft for said roller, bearing means rotatably mounting saidroller on said shaft to permit rotation thereof by thread passing tosaid traverse mechanism, and means for rotating said support shaft toreduce the force resisting rotational movement of the roller on saidshaft and thereby reduce tensional force acting on thread being laid onsaid support surface.

2. In an apparatus for forming annular reinforcing belts for pneumatictires including an extruder for applying a protective coating to alongitudinally moving thread, a winding drum and thread guide traversemechanism for receiving coated thread from the extruder, means forrotating the drum while reciprocating the traverse mechanism across theperipheral surface of the drum to draw coated thread onto the drum andlay the thread in a desired pattern on the drum surface, thread guidemeans for longitudinally directing the thread from the extruder to thetraverse mechanism, and control means for varying the rate of movementof the drum and traverse mechanism in response to variations in thelength of thread between the extruder and winding drum; the improvementwherein said thread guide means includes a roller positioned adjacentthe traverse mechanism for supportably receiving and guiding threadthereto, a support shaft for said roller, bearing means rotatablymounting said roller on said shaft to permit rotation thereof by threadpassing thereover to said traverse mechanism, and means for rotatingsaid support shaft to reduce the force resisting rotational movement ofthe roller on said shaft and thereby reduce the tensional force actingon the thread being laid on the winding drum.

3. Apparatus as defined in claim 2 wherein said means for rotating saidshaft includes means for varying the rotational speed of said shaft indirect proportion to variations in the speed of movement of the windingdrumto minimize variations in tension on the thread passing onto thesurface of the winding drum.

4. Apparatus as defined in claim 3 wherein said control means includesmeans engaging said thread between said extruder and said roller andbeing displaceable in response to varying tension on the thread tolengthen and shorten the thread path between said roller and theextruder, and means for varying the speed of movement of the windingdrum in response to the position of said thread engaging means.

5. A method of winding a continuous thread on a rotating support surfacein a desired pattern which necessitates relatively large increments ofacceleration and deceleration in the velocity of the thread passing ontothe rotating support surface comprising the steps of rotating thesupport surface to longitudinally draw thread onto the surface whilewhile guiding the thread across the surface to lay the thread in adesired path thereon, and applying a feeding force to the thread beingdrawn onto the support surface at those times when the thread isundergoing relatively large increases in acceleration during itsmovement onto the surface to minimize its displacement from the desiredpath due to tension exerted on the thread.

6. A method as defined in claim 5 wherein said thread is guided onto thesurface to lay the thread in a generally zig-zag path thereon, andwherein the feeding force is applied to the thread as the point ofthread lay down moves away from the corners of the zigzag path.

7. A method of winding a continuous thread on a rotating support surfacein a desired pattern comprising the steps of rotating the supportsurface to longitudinally draw thread onto the surface whilereciprocating a thread guide traverse mechanism across the surface tolay the thread in a generally zig-zag path thereon, frictionallyengaging the thread by a rotatable roller to guide the thread to thetraverse mechanism, and applying rotational force to the roller toimpart a feeding force to the thread as the traverse mechanism movesaway from the corners of the zig-zag path while permitting variations inthe rotational speed of the roller in response to variations in thelinear speed of the thread passing thereover.

8. A method as defined in claim 7 wherein the rotatable roller isrotatably mounted on a support shaft and wherein the rotational force isapplied to the roller by rotating the support shaft.

References Cited UNITED STATES PATENTS 2,284,244 5/ 1942 Allquist.

3,047,247 7/ 1962 Kotte 242-45 3,097,805 7/1963 Oberly 24243 3,273,9859/1966 Small et al 24218-XR 3,281,087 10/ 1966 Claiborne et a1 24218STANL'EY N. GILREATH, Primary Examiner W. H. SCHROEDER, AssistantExaminer U.S. c1. X.R, 242-45,

